In-line isolation devices such as in-line disconnect switches are commonly employed in electric power transmission lines where it is desired to permanently or selectively isolate a power line such as an overhead power line. Known isolation devices include a pair of end pieces (which may be referred to as dead ends) connected by an elongate insulator. The end pieces are each clamped to a power line. The power line is then cut between the end pieces so that the isolation device mechanically couples and electrically isolates the two ends of the power line. Examples of devices of this type are disclosed in Canadian Patent No. 2,092,741, U.S. Pat. No. 5,581,051 to Hill, and U.S. Pat. No. 5,942,723 to Laricchia.